In many western countries, a photosensitizer is used to kill cancer cells in the treatment of cancer with the goal of causing minimum harm to the organs and tissues of body. These methods can avoid injury and other negative effects caused by a surgery, and they also reduce the recovery time of the patents. The theory of the photothermal therapy is based on a medium which can convert light into heat to kill the adjacent cancer cells in the process of light-heat conversion. The most familiar source of photosensitizer materials is organic molecules. In a treatment period of 1-30 days, as a result of exposure of the organic photosensitizer to illumination, too much heat generation would affect the body tissues surrounding the cancer cells. Indeed, to reduce the risk that normal organs would be damaged by the heat treatment, developing nano-materials with high efficiency of light-heat conversion would reduce the treatment time substantially. There have recently been many studies focusing on photothermal and photoacoustic imaging. The starting point is based on various types of nanogold, such as a gold nanorod, a gold nanoshell and a gold nanobox to develop a photothermal therapy, especially for photoacoustic imaging agent. However, there are still some substantial problems with the current applications.
At present, various developed photoacoustic imaging agents do not have sufficient imaging effects or retain optical characteristics for a long time. Conventional photoacoustic imaging systems only use nanogold, in which the stability for light and heat is very low under laser, and the nanogold can not actually achieve the purposes of perfect imaging and stability in the bodies of the subjects. Under the illumination of a pulsed laser, the nanogold will deform, thereby losing some of the original optical characteristics by the effect of local high temperature in a short time. Although the nanogold has effects of light and heat, the synthesized nanogold has defects of high toxicity and low biocompatibility, and thus the surface thereof has to be modified, which is time-consuming and troublesome.
In order to overcome the drawbacks in the prior art, a nano-contrast agent with seaurchin structure and the preparation method thereof are disclosed. The particular design in the present invention not only solves the problems described above, but is also easily implemented. Thus, the present invention has utility for the industry.